The purpose of this research is to identify specific oral-facial variations present in the near relatives (1st and 2nd degree) of cleft lip and palate probands. This is a continuation of the project begun 5 years ago to identify non-cleft persons with major genetic liability for transmitting the trait to offspring. We have, so far, found no significance morphologgic variations but the speech functions of parents of cleft children do show an increase in velo-pharyngeal inadequacy. The significance of this finding is unknown. However, we have made a major change in our working hypothesis. Instead of studying relatives of all cleft probands for these oral-facial variations, as is compatible with the multifactorial model of causation of cleft lip and palate, we will study only relatives in multipally affected families, and only those in unilateral linns, for evidence of clefting gene action. The reason for this approach is recent observations we have made on the Danish population of clefts denies those predictions used to support multifactorial inheritance and, instead, they support the presence of a monogenic, dominantly inherited form of both cleft lip and cleft palate within the heterogeneous group of all clefts. Hence, the use of multipally affected families conceivably limits the investigation to a single etiologic cleft type, the one most likely to yeild a positive result. In this study, a series of 15-20 families with at least 2 affecteds in near relatives will be evaluated for (1) morphologic and (2) functional (speech) variations as evidence of minor expression of a monogenic trait. Such minor expressions will be most useful to the genetic counselor in providing recurrence risks for affected families.